The present invention relates to network technology. More specifically, this invention relates generally to network management and specifically relates to troubleshooting network devices that use the Fibre Channel (“FC”) protocol in a network implementing virtualization.
The Switched Port Analyzer (SPAN) feature, sometimes called port mirroring or port monitoring, selects network traffic for analysis by a network analyzer such as a SwitchProbe device or other Remote Monitoring (RMON) probe. The network analyzer is typically attached to a port that is configured to receive a copy of every frame that is sent by a particular host or hosts. This port is called a destination SPAN port. The traffic that is monitored may be ingress traffic (i.e., traffic entering the port) and/or egress traffic (i.e., traffic leaving the port). The port for which ingress and/or egress traffic is monitored is referred to as a source SPAN port. One system for performing SPAN in association with a physical source SPAN port is disclosed in patent application Ser. No. 10/655,452, entitled, “Switch Port Analyzers,” by Kloth et al, which was incorporated by reference above.
FIG. 1 is a simplified diagram illustrating an application of SPAN for use with a physical source SPAN port. In the following description, a physical source SPAN port will be referred to as a source SPAN port having a physical address. In order to initiate a SPAN session, the user configures the SPAN session 102 via a supervisor 104. Specifically, the SPAN session is configured by identifying the source SPAN port and destination SPAN port, as well as indicating whether the traffic to be monitored is ingress and/or egress traffic. The source SPAN port is typically defined by identifying both the line card and port of the line card. The destination SPAN port is also typically defined by identifying both the line card and port of the line card. For instance, a Fibre Channel port 1 of a line card 2 may be denoted as fc2/1
In this example, there are two different line cards, referred to as Intelligent Line Cards (ILCs), first line card (ILC1) 106 and second line card (ILC2) 108 having corresponding forwarding engines 110 and 112, respectively. Each network device (e.g., host or disk) is coupled to a different physical port. Specifically, with respect to the first line card 106, host 114 is associated with port fc1/1 116, the SPAN destination (SD) port 118 is associated with port fc1/5 120, and disk1 122 is associated with port fc1/7 124. With respect to the second line card 108, disk2 126 is associated with port fc2/1 128.
As one example of the application of SPAN in association with a physical source SPAN port, a user may choose to SPAN all traffic entering port fc1/1 116 and send a replica of this traffic to a SD port that is configured. In this example, the SD port 118 is configured to be port fc1/5 120. Thus, the forwarding engine 110 of the first line card (ILC1) 106 forwards frames entering port fc1/1 116 to the destination address identified in the headers of those frames, per the normal Fibre Channel forwarding protocol. In addition, the forwarding engine 110 replicates the frames so that a replica of this traffic is also forwarded to the SD port, port fc1/5 120, so that the traffic may be analyzed. Of course, the user may similarly choose to configure or select a different SD port for this particular SPAN session.
While it is helpful to perform SPAN for a physical source SPAN port, virtualization is often desirable for a variety of reasons. For instance, it may be desirable to establish virtualization of storage within a network to enable one or more physical storage locations to be logically represented by a virtual storage location. Virtualization of storage within a network such as a Storage Area Network (SAN) may be accomplished via a variety of mechanisms. One such mechanism is set forth in patent application Ser. No. 10/056,238, entitled “Methods and Apparatus for Implementing Virtualization of Storage within a Storage Area Network,” by Edsall et al, which is incorporated herein by reference for all purposes. In this manner, a physical address may be mapped to a virtual address for use in accessing a virtual storage location in a SAN.
It is also possible to configure a “virtual port.” This may be accomplished via switch-based virtualization (i.e., virtualization implemented in the switches, rather than in the hosts or storage devices). One mechanism for implementing virtual ports via a mechanism such as switch-based virtualization is further described in patent application Ser. No. 10/045,883, entitled “Methods and Apparatus for Implementing Virtualization of Storage within a Storage Area Network Through a Virtual Enclosure,” Kumar et al, which is incorporated herein by reference for all purposes. Specifically, a virtual enclosure representing one or more virtual storage units may be created, where each of the virtual storage units represents one or more physical storage locations of one or more physical storage units of a SAN. This virtual enclosure may have one or more associated virtual enclosure ports (i.e., virtual ports). Each virtual port is typically associated with a physical port of a network device within the SAN. The physical port of the network device is then instructed to handle messages addressed to the virtual port. Since each port may manage virtualization of its own traffic, virtualization capacity may scale with the number of ports on a switch.
While it is possible to configure a SPAN session for a physical source SPAN port, there is currently no mechanism to monitor traffic to or from a particular virtual port. In fact, in order to capture all the traffic related to a particular virtual interface, one would have to monitor all the physical links that carry traffic for the virtual interface. The irrelevant traffic would then need to be filtered out. This would therefore require a huge amount of fabric bandwidth and resources, even though one is only interested in traffic on a specific virtual interface. As a result, this approach is extremely inefficient.
Moreover, it is not practical to determine the physical links on which the traffic for a virtual port is flowing. Specifically, in order to identify these physical links, the routing information would need to be obtained and analyzed. However, since the routing information changes dynamically, identifying these physical links would be a difficult and computationally expensive process.
Even if it were possible to identify and monitor the physical links on which the traffic for a virtual port is flowing, a large amount of traffic for a virtual port may not travel outside the switch. As a result, such traffic would not cross a physical link. Unfortunately, the SPAN feature is not capable of capturing such internal traffic.
Moreover, a key advantage of network-based (i.e., switch-based) virtualization is that the hosts or the disks can be moved anywhere in the network, since the virtual port continues to retain the same identifier. However, according to the SPAN implementation set forth above, the SPAN configuration would need to be modified to reflect the new physical location of the hosts/disks. As a result, the SPAN configuration would need to be immediately modified for every relocation of a physical node. Otherwise there would be a window of time during which traffic would not be SPANed.
In view of the above, it would be beneficial if traffic associated with a virtual port could be effectively monitored via a SPAN feature.